E-UTRAN is a wireless communication system that is evolved from the universal mobile telecommunications system (UMTS) terrestrial radio access network system. As set forth currently at 3GPP (third generation partnership project) TS 36.212, there are to be 188 different turbo frames for turbo codes. Channel codes are applied at the transmitting device to establish protection of data (user data or control data) against many kind of errors caused by disturbing factors in a wireless air interface channel. Then the coded data has to be decoded at the receiver to recover original data at a receiver. Turbo codes are commonly used for data protection between two or more communication devices like mobile phones, network access nodes (e.g., e-NodeB, NodeB, base station, wireless local area network access point). Such devices use a turbo decoder to decode this coded data.
One element of E-UTRAN (though not limited to only that wireless protocol) is the use of high speed data links (e.g., data transfer speed higher than about 20 Mbps). At such high speed and especially with such a high number of channel codes as noted above for 3GPP TS 36.212, the receiver/turbo decoder needs to process at quite a high rate to decode properly in a real time or near real time manner as the coded data is being received.
Generally there are two simple approaches to such high speed turbo decoding: employ a high clock rate on the ASIC (application specific integrated circuit) that embodies the turbo decoder to keep up with the incoming data rate, or to use parallel processing which allows slower processing on each of the parallel streams without falling behind the incoming data.
A higher ASIC clock rate is limited by higher power consumption, limits to semiconductor technology used to make the ASIC, and a higher end-user price for the device with the high-clock-rate ASIC. Parallel processing enables a faster decoder while avoiding some of those same limitations. Particularly in portable wireless devices (e.g., mobile stations or other portable user equipment UE), power consumption becomes an important design consideration.
Relevant to these teachings are two documents by the same inventor as for the invention detailed herein: U.S. Pat. No. 7,272,771 issued on Sep. 18, 2007 and entitled “NOISE AND QUALITY DETECTOR FOR USE WITH TURBO CODED SIGNALS” (hereinafter, the Noise and Quality Detector reference); and co-pending U.S. patent application Ser. No. 11/810,199 filed on Jun. 4, 2007 and entitled “MULTIPLE ACCESS FOR PARALLEL TURBO DECODER” (hereinafter, the Multiple Access Decoder reference). Each of these documents are incorporated herein by reference in their entirety.
Embodiments of the invention detailed below may simplify some of the operations detailed in those two references noted immediately above, and so can be particularly advantageous for high-speed data links especially where there is a large number of different turbo frames as in 3GPP TS 36.212.